Over time, updates may cause rows on data pages to change location lowering the degree of clustering that exists between an index and the data pages. Reorganizing a table with respect to a chosen index reclusters the data. A clustered index is most useful for columns that have range predicates because it allows better sequential access of data in the base table. This results in fewer page fetches, since like values are on the same data page.
In general, only one of the indexes in a table can have a high degree of clustering.
To check the degree of clustering for an index, double-click on its node to display the Index Statistics window. The cluster ratio or cluster factor values are shown in this window. If the value is low, consider reorganizing the table's data.
For more information, see the section on reorganizing table data in the Administration Guide.
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